Impact of fermented foods consumption on gastrointestinal wellbeing in healthy adults: a systematic review and meta-analysis

Arghya Mukherjee^1,2*Dominic N. Farsi³Enriqueta Garcia-Gutierrez^1,2,4Ecem Akan⁵Jose Angel Salas Millan^2,6Ljupco Angelovski⁷Thomas Bintsis⁸Amaury Gerard⁹Ziba Guley¹⁰Sumeye Kabakci¹¹Minna Kahala¹²Ryma Merabti^13,14Pavli Foteini¹⁵Elisa Salvetti¹⁶Cem Karagozlu¹⁷Nurcan Baglam¹⁸Bahtir Hyseni¹⁹Simona Bavaro²⁰Konstantinos Papadimitriou²¹Eun-Hee Doo²²Christophe Chassard³Smilja Praćer²³Guy Vergères²⁴Paul David Cotter^1,2,25Sandra Mojsova^26*

• ¹Department of Food Biosciences, Teagasc, Fermoy, Cork, Ireland
• ²University College Cork APC Microbiome Institute, Cork, Ireland
• ³Human Nutrition Unit, INRAE, Université Clermont-Auvergne, Clermont-Ferrand, France
• ⁴Universidad Politecnica de Cartagena Escuela Tecnica Superior de Ingenieria Agronomica, Cartagena, Spain
• ⁵Aydin Adnan Menderes Universitesi, Aydın, Türkiye
• ⁶University College Cork, Cork, Ireland
• ⁷Saints Cyril and Methodius University in Skopje Faculty of Veterinary Medicine, Skopje, North Macedonia
• ⁸Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
• ⁹Brewing & Food Science Unit, LABIRIS, Anderlecht, Belgium
• ¹⁰Department of Food Engineering, Alanya Alaaddin Keykubat University, Alanya, Türkiye
• ¹¹National Food Reference Laboratory, Ministry of Agriculture and Forestry, Ankara, Türkiye
• ¹²Luonnonvarakeskus, Helsinki, Finland
• ¹³Faculty of Natural and Life Sciences, Department of Cellular and Molecular Biology, Abbes Laghrour University, Khenchela, Algeria
• ¹⁴Universite Freres Mentouri Constantine 1 Institut de la Nutrition de l'Alimentation et des Technologies Agro-Alimentaires, Constantine, Algeria
• ¹⁵Department of Food Sciences and Nutrition, University of Malta, Msida, Malta
• ¹⁶Universita degli Studi di Verona Dipartimento di Biotecnologie, Verona, Italy
• ¹⁷Ege Universitesi Sut Teknolojisi Bolumu, Izmir, Türkiye
• ¹⁸Sivas Cumhuriyet Universitesi Beslenme ve Diyetetik Anabilim Dali, Sivas, Türkiye
• ¹⁹Faculty of Food Technology, University “Isa Boletini” in Mitrovica, Kosovo, Mitrovica, Serbia
• ²⁰Istituto di Scienze delle Produzioni Alimentari Consiglio Nazionale delle Ricerche, Bari, Italy
• ²¹Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
• ²²Yuhan University, Bucheon-si, Republic of Korea
• ²³Univerzitet u Beogradu Institut za bioloska istrazivanja Sinisa Stankovic, Belgrade, Serbia
• ²⁴Agroscope, Bern, Switzerland
• ²⁵VistaMilk, Cork, Ireland
• ²⁶Faculty of Veterinary Medicine Skopje, Saints Cyril and Methodius University of Skopje, Skopje, North Macedonia

Objective: In recent years, the consumption of fermented foods (FFs) has been linked with gastrointestinal health and wellbeing. Here, we systematically review and meta-analyse the currently available evidence relating to this as part of the COST Action PIMENTO and guided by the European Food Safety Authority (EFSA) health claim dossiers. Methods: MEDLINE, Scopus and Cochrane CENTRAL bibliographic libraries were searched for relevant literature up to 31st January 2025. All eligible studies were included for narrative review as per EFSA guidelines, but only randomised controlled trials (RCTs) were considered for meta-analyses. Risk of bias, mechanisms of action, bioactive compounds and safety were additionally discussed. Data was pooled using mean difference (MD)/standardized MD for continuous data and relative risk (RR) for dichotomous data. Certainty of evidence was evaluated through GRADE assessment. Results: A total of 25 studies (19 RCTs included in meta-analysis) with 4,328 participants were included in the systematic review. Meta-analysis demonstrated the beneficial impact of FF consumption on frequency of bowel movements (MD 0.60, CI 0.04, 1.16, p = 0.04, I2 = 74%), stool consistency (Bristol Stool Form Scale) (MD 0.25, CI 0.03, 0.47, p = 0.03, I2 = 72%), gastrointestinal symptoms (SMD -0.60, CI -1.05, -0.15, p = 0.009, I2 = 90%) and intestinal transit time (-13.65 CI -21.88, -5.43, p = 0.001, I2 = 95%), among others. Certainty of evidence was highly variable and mostly low. Conclusion: Our analysis suggests that FF consumption beneficially impacts the frequency of bowel movements, stool consistency, incidence of hard stools, intestinal transit time, abdominal symptoms, bloating, borborygmi, flatulence and degree of constipation. Systematic Review Registration: This study was registered at the Open Science Framework (osf.io/q8yzd; associated project: osf.io/4vu5t)